Devices and methods for robust measurement and data receiving

ABSTRACT

Devices and methods of simultaneous data reception and measurement are generally described. A UE transmits to an eNB antenna capacity and receives a Beamformed Reference Signal (BRS) configuration in response. Beamformed signals from the eNB include a BRS subframe in accordance with the BRS configuration. The BRS subframe has a BRS whose structure depends on the UE antenna capacity. If the UE has a single antenna panels, neither an EPDCCH nor a PDSCH for the UE is in the BRS frame. If the UE has a single antenna panels and multiple ports or multiple antenna panels, the BRS may contain an EPDCCH or PDSCH for the UE as different ports or antenna panels may be assigned different functionality. The UE measures BRS Received Power (BRS-RP) of the BRS, transmits a BRS report based on the BRS-RP and selects an optimal beam based on BRS-RPs from BRSs of the beams.

PRIORITY CLAIM

This application is a continuation of U.S. Patent Application No.15/770,948, filed Apr. 25, 2018, which is a U.S. National StageApplication under 35 U.S.C. 371 from International Application No.PCT/US2016/021440, filed Mar. 9, 2016, which is a continuation of andclaims priority under 35 U.S.C. § 120 to International Application No.PCT/CN2015/092921, filed Oct. 27, 2015, each of which is incorporatedherein by reference in their entirety.

TECHNICAL FIELD

Embodiments pertain to Multiple Input Multiple Output (MIMO)communication in cellular networks. Some embodiments relate to initialaccess in MIMO communication in cellular and wireless local area network(WLAN) networks, including Third Generation Partnership Project LongTerm Evolution (3GPP LTE) networks and LTE advanced (LTE-A) networks aswell as 4^(th) generation (4G) networks and 5^(th) generation (5G)networks.

BACKGROUND

With the ever-increasing demand for bandwidth, network operators haveturned to Multiple Input Multiple Output (MIMO) systems to increase theamount of data simultaneously delivered. MIMO systems use multipathsignal propagation to communicate with one or more user equipments (UEs)via multiple signals transmitted by the same evolved NodeB (eNB) on thesame or overlapping frequencies that would interfere with each other ifthey were on the same path. This increase in uplink or downlink data maybe dedicated to one UE, increasing the effective bandwidth for that UEby the number of spatial streams (Single User MIMO or SU-MIMO) or may bespread across multiple UEs using different spatial streams for each UE(Multiple User MIMO or MU-MIMO). MU-MIMO systems may use beamforming, inwhich multiple signals may be transmitted in parallel in differentdirections. MU-MIMO systems, however, may complicate a variety oftransmission and reception matters. For example, the use of multiplebeams may engender issues with simultaneous measurement and datareceiving in a UE that uses receive beamforming.

BRIEF DESCRIPTION OF THE FIGURES

In the figures, which are not necessarily drawn to scale, like numeralsmay describe similar components in different views. Like numerals havingdifferent letter suffixes may represent different instances of similarcomponents. The figures illustrate generally, by way of example, but notby way of limitation, various embodiments discussed in the presentdocument.

FIG. 1 is a functional diagram of a wireless network in accordance withsome embodiments.

FIG. 2 illustrates components of a communication device in accordancewith some embodiments.

FIG. 3 illustrates a block diagram of a communication device inaccordance with some embodiments.

FIG. 4 illustrates another block diagram of a communication device inaccordance with some embodiments.

FIG. 5 illustrates communications between an eNB and UE in accordancewith some embodiments.

FIG. 6 illustrates a method of Beamformed Reference Signal (BRS)measurement in accordance with some embodiments.

DETAILED DESCRIPTION

The following description and the drawings sufficiently illustratespecific embodiments to enable those skilled in the art to practicethem. Other embodiments may incorporate structural, logical, electrical,process, and other changes. Portions and features of some embodimentsmay be included in, or substituted for, those of other embodiments.Embodiments set forth in the claims encompass all available equivalentsof those claims.

FIG. 1 shows an example of a portion of an end-to-end networkarchitecture of a Long Term Evolution (LTE) network with variouscomponents of the network in accordance with some embodiments. As usedherein, an LTE network refers to both LTE and LTE Advanced (LTE-A)networks as well as other versions of LTE networks to be developed,including 4G and 5G networks. The network 100 may comprise a radioaccess network (RAN) (e.g., as depicted, the evolved universalterrestrial radio access network (E-UTRAN) 101 and core network 120(e.g., shown as an evolved packet core (EPC)) coupled together throughan S1 interface 115. For convenience and brevity, only a portion of thecore network 120, as well as the RAN 101, is shown in the example.

The core network 120 may include a mobility management entity (MME) 122,serving gateway (serving GW) 124, and packet data network gateway (PDNGW) 126. The RAN 101 may include evolved node Bs (eNBs) 104 (which mayoperate as base stations) for communicating with user equipment (UE)102. The eNBs 104 may include macro eNBs 104 a and low power (LP) eNBs104 b. The eNBs 104 and UEs 102 may employ the synchronizationtechniques as described herein.

The MME 122 may be similar in function to the control plane of legacyServing GPRS Support Nodes (SGSN). The MME 122 may manage mobilityaspects in access such as gateway selection and tracking area listmanagement. The serving GW 124 may terminate the interface toward theRAN 101, and route data packets between the RAN 101 and the core network120. In addition, the serving GW 124 may be a local mobility anchorpoint for inter-eNB handovers and also may provide an anchor forinter-3GPP mobility. Other responsibilities may include lawfulintercept, charging, and some policy enforcement. The serving GW 124 mayserve as the local mobility anchor for data bearers when a UE 102 movesbetween eNBs 104. The serving GW 124 may retain information about thebearers when the UE 102 is in idle state (known as ECM_IDLE) andtemporarily buffer downlink data while the MME 122 initiates paging ofthe UE 102 to re-establish the bearers.

The serving GW 124 and the MME 122 may be implemented in one physicalnode or separate physical nodes. The MME 122 may be connected with aHome Subscriber Server (HSS) 128 that contains user-related andsubscription-related information. The HSS 128 may support mobilitymanagement, call and session establishment support, user authenticationand access authorization. The protocols running between the UE 102 andthe EPC 124 are known as the Non-Access Stratum (NAS) protocol. Otherprotocols, including RRC, Packet Data Convergence Protocol (PDCP), RadioLayer Control (RLC), Media Access Control (MAC) and Physical Layer(PHY), are terminated in the eNB 104. The NAS layer performs EPS bearermanagement, authentication for LTE, mobility support for idle mode UEs,paging origination for idle mode UEs, and security handling.

The RRC layer may provide radio resource management, RRC connectionmanagement, and mobility support for connected mode UEs 102. As the RRCcontrol message between the eNB 104 and the UE 102, the RRC layer mayhandle the broadcast of system information, which is cell-specific, anda dedicated RRC control message, which is UE-specific. In addition, theRRC layer may perform paging, radio bearer control, and control of UEmeasurement reporting, among others. The PDCP layer may process RRCmessages in the control plane and IP packets in the user plane.Depending on the radio bearer, the PDCP layer may perform headercompression, security (integrity protection and ciphering), and supportfor reordering and retransmission during handover. There may be one PDCPentity per radio bearer. The RLC layer may provide segmentation andreassembly of upper layer packets to adapt the packets to a size thatcan actually be transmitted over the radio interface. For a radio bearerusing error-free transmission, the RLC layer may also performretransmission to recover from packet losses. Additionally, the RLClayer may perform reordering to compensate for out-of-order receptiondue to HARQ (Hybrid Automatic Repeat reQuest) operation in the layerbelow. There may be one RLC entity per radio bearer. The MAC layer maymultiplex the data from different radio bearers. By deciding the amountof data that can be transmitted from each radio bearer and instructingthe RLC layer as to the size of packets to provide, the MAC layer aimsto achieve the negotiated QoS (Quality of Service) for each radiobearer. For the uplink, this process may include reporting to the eNB104 the amount of buffered data for transmission. The PHY layer mayperform CRC insertion, channel coding, physical channel HARQ processing,channel interleaving, scrambling, modulation, layer mapping andpre-coding for transport channels. Power control and cell searchprocedures are also performed as the PHY functions.

The PDN GW 126 may terminate a SGi interface toward the packet datanetwork (PDN). The PDN GW 126 may route data packets between the EPC 120and the external PDN, and may perform policy enforcement and chargingdata collection. The PDN GW 126 may be responsible for IP addressallocation for the UEs 102, as well as QoS enforcement and flow-basedcharging according to the rules from the PCRF (Policy and Charging RulesFunctions). The PDN GW 126 may also provide an anchor point for mobilitydevices with non-LTE access. The external PDN can be any kind of IPnetwork, as well as an IP Multimedia Subsystem (IMS) domain. The PDN GW126 and the serving GW 124 may be implemented in a single physical nodeor separate physical nodes.

The eNBs 104 (macro and micro) may terminate the air interface protocoland may be the first point of contact for a UE 102. In some embodiments,an eNB 104 may fulfill various logical functions for the RAN 101including, but not limited to, RNC (radio network controller functions)such as radio bearer management, uplink and downlink dynamic radioresource management and data packet scheduling, and mobility management.In accordance with embodiments, UEs 102 may be configured to communicateorthogonal frequency division multiplexed (OFDM) communication signalswith an eNB 104 over a multicarrier communication channel in accordancewith an OFDMA communication technique. The OFDM signals may comprise aplurality of orthogonal subcarriers.

The S1 interface 115 may be the interface that separates the RAN 101 andthe EPC 120. It may be split into two parts: the S1-U, which may carrytraffic data between the eNBs 104 and the serving GW 124, and theS1-MME, which may be a signaling interface between the eNBs 104 and theMME 122. The X2 interface may be the interface between eNBs 104. The X2interface may comprise two parts, the X2-C and X2-U. The X2-C may be thecontrol plane interface between the eNBs 104, while the X2-U may be theuser plane interface between the eNBs 104.

With cellular networks, LP cells 104 b may be typically used to extendcoverage to indoor areas where outdoor signals do not reach well, or toadd network capacity in areas with dense usage. In particular, it may bedesirable to enhance the coverage of a wireless communication systemusing cells of different sizes, macrocells, microcells, picocells, andfemtocells, to boost system performance. The cells of different sizesmay operate on the same frequency band, or may operate on differentfrequency bands with each cell operating in a different frequency bandor only cells of different sizes operating on different frequency bands.As used herein, the term LP eNB refers to any suitable relatively LP eNBfor implementing a smaller cell (smaller than a macro cell) such as afemtocell, a picocell, or a microcell. Femtocell eNBs may be typicallyprovided by a mobile network operator to its residential or enterprisecustomers. A femtocell may be typically the size of a residentialgateway or smaller and generally connect to a broadband line. Thefemtocell may connect to the mobile operator's mobile network andprovide extra coverage in a range of typically 30 to 50 meters. Thus, aLP eNB 104 b might be a femtocell eNB since it is coupled through thePDN GW 126. Similarly, a picocell may be a wireless communication systemtypically covering a small area, such as in-building (offices, shoppingmalls, train stations, etc.), or more recently in-aircraft. A picocelleNB may generally connect through the X2 link to another eNB such as amacro eNB through its base station controller (BSC) functionality. Thus,LP eNB may be implemented with a picocell eNB since it may be coupled toa macro eNB 104 a via an X2 interface. Picocell eNBs or other LP eNBs LPeNB 104 b may incorporate some or all functionality of a macro eNB LPeNB 104 a. In some cases, this may be referred to as an access pointbase station or enterprise femtocell.

Communication over an LTE network may be split up into 10 ms frames,each of which may contain ten 1 ms subframes. Each subframe of theframe, in turn, may contain two slots of 0.5 ms. Each subframe may beused for uplink (UL) communications from the UE to the eNB or downlink(DL) communications from the eNB to the UE. The eNB may scheduletransmissions over a variety of frequency bands. The allocation ofresources in subframes used in one frequency band and may differ fromthose in another frequency band. Each slot of the subframe may contain6-7 OFDM symbols, depending on the system used. In some embodiments, thesubframe may contain 12 subcarriers. A downlink resource grid may beused for downlink transmissions from an eNB to a UE, while an uplinkresource grid may be used for uplink transmissions from a UE to an eNBor from a UE to another UE. The resource grid may be a time-frequencygrid, which is the physical resource in the downlink in each slot. Thesmallest time-frequency unit in a resource grid may be denoted as aresource element (RE). Each column and each row of the resource grid maycorrespond to one OFDM symbol and one OFDM subcarrier, respectively. Theresource grid may contain resource blocks (RBs) that describe themapping of physical channels to resource elements and physical RBs(PRBs). A PRB may be the smallest unit of resources that can beallocated to a UE. A resource block may be 180 kHz wide in frequency and1 slot long in time. In frequency, resource blocks may be either 12×15kHz subcarriers or 24×7.5 kHz subcarriers wide. For most channels andsignals, 12 subcarriers may be used per resource block, dependent on thesystem bandwidth. In Frequency Division Duplexed (FDD) mode, both theuplink and downlink frames may be 10 ms and frequency (full-duplex) ortime (half-duplex) separated. In Time Division Duplexed (TDD), theuplink and downlink subframes may be transmitted on the same frequencyand are multiplexed in the time domain. The duration of the resourcegrid 400 in the time domain corresponds to one subframe or two resourceblocks. Each resource grid may comprise 12 (subcarriers)*14(symbols)=168 resource elements.

There may be several different physical downlink channels that areconveyed using such resource blocks, including the physical downlinkcontrol channel (PDCCH) and the physical downlink shared channel(PDSCH). Each downlink subframe may be partitioned into the PDCCH andthe PDSCH. The PDCCH may normally occupy the first two symbols of eachsubframe and carry, among other things, information about the transportformat and resource allocations related to the PDSCH channel, as well asH-ARQ information related to the uplink shared channel. The PDSCH maycarry user data and higher layer signaling to a UE and occupy theremainder of the subframe. Typically, downlink scheduling (assigningcontrol and shared channel resource blocks to UEs within a cell) may beperformed at the eNB based on channel quality information provided fromthe UEs to the eNB, and then the downlink resource assignmentinformation may be sent to each UE on the PDCCH used for (assigned to)the UE. The PDCCH may contain downlink control information (DCI) in oneof a number of formats that indicate to the UE how to find and decodedata, transmitted on PDSCH in the same subframe, from the resource grid.The DCI format may provide details such as number of resource blocks,resource allocation type, modulation scheme, transport block, redundancyversion, coding rate etc. Each DCI format may have a cyclic redundancycode (CRC) and be scrambled with a Radio Network Temporary Identifier(RNTI) that identifies the target UE for which the PDSCH is intended.Use of the UE-specific RNTI may limit decoding of the DCI format (andhence the corresponding PDSCH) to only the intended UE.

In addition to the PDCCH, an enhanced PDCCH (EPDCCH) may be used by theeNB and UE. Unlike the PDCCH, the EPDCCH may be disposed in the resourceblocks normally allocated for the PDSCH. Different UEs may havedifferent EPDCCH configurations that are configured via Radio ResourceControl (RRC) signaling. Each UE may be configured with sets of EPDCCHs,and the configuration can also be different between the sets. EachEPDCCH set may have 2, 4, or 8 PRB pairs. In some embodiments, resourceblocks configured for EPDCCHs in a particular subframe may be used forPDSCH transmission if the resource blocks are not used for the EPDCCHtransmissions during the subframe.

Similarly, different physical uplink channels may include the PhysicalUplink Control Channel (PUCCH) used by the UE to send Uplink ControlInformation (UCI) to the eNB and request a Physical Uplink SharedChannel (PUSCH) used to provide uplink data to the eNB. The PUCCH may bemapped to an UL control channel resource defined by an orthogonal covercode and two resource blocks, consecutive in time, with hoppingpotentially at the boundary between adjacent slots. The PUCCH may takeseveral different formats, with the UCI containing information dependenton the format. Specifically, the PUCCH may contain a scheduling request(SR) that may permit the UE to request uplink resources for the PUSCH,acknowledgement responses/retransmission requests (ACK/NACK) or aChannel Quality Indication (CQI)/Channel State Information (CSI). TheCQI/CSI may indicate to the eNB an estimate of the current downlinkchannel conditions as seen by the UE to aid channel-dependent schedulingand, if one MIMO transmission mode is configured to the UE, may includeMIMO-related feedback (e.g. Precoder matrix indication, PMI).

Embodiments described herein may be implemented into a system using anysuitably configured hardware and/or software. FIG. 2 illustratescomponents of a UE in accordance with some embodiments. At least some ofthe components shown may be used in an eNB or MME, for example, such asthe UE 102 or eNB 104 shown in FIG. 1. The UE 200 and other componentsmay be configured to use the synchronization signals as describedherein. The UE 200 may be one of the UEs 102 shown in FIG. 1 and may bea stationary, non-mobile device or may be a mobile device. In someembodiments, the UE 200 may include application circuitry 202, basebandcircuitry 204, Radio Frequency (RF) circuitry 206, front-end module(FEM) circuitry 208 and one or more antennas 210, coupled together atleast as shown. At least some of the baseband circuitry 204, RFcircuitry 206, and FEM circuitry 208 may form a transceiver. In someembodiments, other network elements, such as the eNB may contain some orall of the components shown in FIG. 2. Other of the network elements,such as the MME, may contain an interface, such as the S1 interface, tocommunicate with the eNB over a wired connection regarding the UE.

The application or processing circuitry 202 may include one or moreapplication processors. For example, the application circuitry 202 mayinclude circuitry such as, but not limited to, one or more single-coreor multi-core processors. The processor(s) may include any combinationof general-purpose processors and dedicated processors (e.g., graphicsprocessors, application processors, etc.). The processors may be coupledwith and/or may include memory/storage and may be configured to executeinstructions stored in the memory/storage to enable various applicationsand/or operating systems to run on the system.

The baseband circuitry 204 may include circuitry such as, but notlimited to, one or more single-core or multi-core processors. Thebaseband circuitry 204 may include one or more baseband processorsand/or control logic to process baseband signals received from a receivesignal path of the RF circuitry 206 and to generate baseband signals fora transmit signal path of the RF circuitry 206. Baseband processingcircuitry 204 may interface with the application circuitry 202 forgeneration and processing of the baseband signals and for controllingoperations of the RF circuitry 206. For example, in some embodiments,the baseband circuitry 204 may include a second generation (2G) basebandprocessor 204 a, third generation (3G) baseband processor 204 b, fourthgeneration (4G) baseband processor 204 c, and/or other basebandprocessor(s) 204 d for other existing generations, generations indevelopment or to be developed in the future (e.g., fifth generation(5G), 6G, etc.). The baseband circuitry 204 (e.g., one or more ofbaseband processors 204 a-d) may handle various radio control functionsthat enable communication with one or more radio networks via the RFcircuitry 206. The radio control functions may, include, but are notlimited to, signal modulation/demodulation, encoding/decoding, radiofrequency shifting, etc. In some embodiments, modulation/demodulationcircuitry of the baseband circuitry 204 may include FFT, precoding,and/or constellation mapping/demapping functionality. In someembodiments, encoding/decoding circuitry of the baseband circuitry 204may include convolution, tail-biting convolution, turbo, Viterbi, and/orLow Density Parity Check (LDPC) encoder/decoder functionality.Embodiments of modulation/demodulation and encoder/decoder functionalityare not limited to these examples and may include other suitablefunctionality in other embodiments.

In some embodiments, the baseband circuitry 204 may include elements ofa protocol stack such as, for example, elements of an evolved universalterrestrial radio access network (EUTRAN) protocol including, forexample, physical (PHY), media access control (MAC), radio link control(RLC), packet data convergence protocol (PDCP), and/or radio resourcecontrol (RRC) elements. A central processing unit (CPU) 204 e of thebaseband circuitry 204 may be configured to run elements of the protocolstack for signaling of the PHY, MAC, RLC, PDCP and/or RRC layers. Insome embodiments, the baseband circuitry may include one or more audiodigital signal processor(s) (DSP) 204 f. The audio DSP(s) 204 f may beinclude elements for compression/decompression and echo cancellation andmay include other suitable processing elements in other embodiments.Components of the baseband circuitry may be suitably combined in asingle chip, a single chipset, or disposed on a same circuit board insome embodiments. In some embodiments, some or all of the constituentcomponents of the baseband circuitry 204 and the application circuitry202 may be implemented together such as, for example, on a system on achip (SOC).

In some embodiments, the baseband circuitry 204 may provide forcommunication compatible with one or more radio technologies. Forexample, in some embodiments, the baseband circuitry 204 may supportcommunication with an evolved universal terrestrial radio access network(E-UTRAN) and/or other wireless metropolitan area networks (WMAN), awireless local area network (WLAN) a wireless personal area network(WPAN). Embodiments in which the baseband circuitry 204 is configured tosupport radio communications of more than one wireless protocol may bereferred to as multi-mode baseband circuitry. In some embodiments, thedevice can be configured to operate in accordance with communicationstandards or other protocols or standards, including Institute ofElectrical and Electronic Engineers (IEEE) 802.16 wireless technology(WiMax), IEEE 802.11 wireless technology (WiFi) including IEEE 802.11ad, which operates in the 60 GHz millimeter wave spectrum, various otherwireless technologies such as global system for mobile communications(GSM), enhanced data rates for GSM evolution (EDGE), GSM EDGE radioaccess network (GERAN), universal mobile telecommunications system(UMTS), UMTS terrestrial radio access network (UTRAN), or other 2G, 3G,4G, 5G, etc. technologies either already developed or to be developed.

RF circuitry 206 may enable communication with wireless networks usingmodulated electromagnetic radiation through a non-solid medium. Invarious embodiments, the RF circuitry 206 may include switches, filters,amplifiers, etc. to facilitate the communication with the wirelessnetwork. RF circuitry 206 may include a receive signal path which mayinclude circuitry to down-convert RF signals received from the FEMcircuitry 208 and provide baseband signals to the baseband circuitry204. RF circuitry 206 may also include a transmit signal path which mayinclude circuitry to up-convert baseband signals provided by thebaseband circuitry 204 and provide RF output signals to the FEMcircuitry 208 for transmission.

In some embodiments, the RF circuitry 206 may include a receive signalpath and a transmit signal path. The receive signal path of the RFcircuitry 206 may include mixer circuitry 206 a, amplifier circuitry 206b and filter circuitry 206 c. The transmit signal path of the RFcircuitry 206 may include filter circuitry 206 c and mixer circuitry 206a. RF circuitry 206 may also include synthesizer circuitry 206 d forsynthesizing a frequency for use by the mixer circuitry 206 a of thereceive signal path and the transmit signal path. In some embodiments,the mixer circuitry 206 a of the receive signal path may be configuredto down-convert RF signals received from the FEM circuitry 208 based onthe synthesized frequency provided by synthesizer circuitry 206 d. Theamplifier circuitry 206 b may be configured to amplify thedown-converted signals and the filter circuitry 206 c may be a low-passfilter (LPF) or band-pass filter (BPF) configured to remove unwantedsignals from the down-converted signals to generate output basebandsignals. Output baseband signals may be provided to the basebandcircuitry 204 for further processing. In some embodiments, the outputbaseband signals may be zero-frequency baseband signals, although thisis not a requirement. In some embodiments, mixer circuitry 206 a of thereceive signal path may comprise passive mixers, although the scope ofthe embodiments is not limited in this respect.

In some embodiments, the mixer circuitry 206 a of the transmit signalpath may be configured to up-convert input baseband signals based on thesynthesized frequency provided by the synthesizer circuitry 206 d togenerate RF output signals for the FEM circuitry 208. The basebandsignals may be provided by the baseband circuitry 204 and may befiltered by filter circuitry 206 c. The filter circuitry 206 c mayinclude a low-pass filter (LPF), although the scope of the embodimentsis not limited in this respect.

In some embodiments, the mixer circuitry 206 a of the receive signalpath and the mixer circuitry 206 a of the transmit signal path mayinclude two or more mixers and may be arranged for quadraturedownconversion and/or upconversion respectively. In some embodiments,the mixer circuitry 206 a of the receive signal path and the mixercircuitry 206 a of the transmit signal path may include two or moremixers and may be arranged for image rejection (e.g., Hartley imagerejection). In some embodiments, the mixer circuitry 206 a of thereceive signal path and the mixer circuitry 206 a may be arranged fordirect downconversion and/or direct upconversion, respectively In someembodiments, the mixer circuitry 206 a of the receive signal path andthe mixer circuitry 206 a of the transmit signal path may be configuredfor super-heterodyne operation.

In some embodiments, the output baseband signals and the input basebandsignals may be analog baseband signals, although the scope of theembodiments is not limited in this respect. In some alternateembodiments, the output baseband signals and the input baseband signalsmay be digital baseband signals. In these alternate embodiments, the RFcircuitry 206 may include analog-to-digital converter (ADC) anddigital-to-analog converter (DAC) circuitry and the baseband circuitry204 may include a digital baseband interface to communicate with the RFcircuitry 206.

In some dual-mode embodiments, a separate radio IC circuitry may beprovided for processing signals for each spectrum, although the scope ofthe embodiments is not limited in this respect.

In some embodiments, the synthesizer circuitry 206 d may be afractional-N synthesizer or a fractional N/N+1 synthesizer, although thescope of the embodiments is not limited in this respect as other typesof frequency synthesizers may be suitable. For example, synthesizercircuitry 206 d may be a delta-sigma synthesizer, a frequencymultiplier, or a synthesizer comprising a phase-locked loop with afrequency divider.

The synthesizer circuitry 206 d may be configured to synthesize anoutput frequency for use by the mixer circuitry 206 a of the RFcircuitry 206 based on a frequency input and a divider control input. Insome embodiments, the synthesizer circuitry 206 d may be a fractionalN/N+1 synthesizer.

In some embodiments, frequency input may be provided by a voltagecontrolled oscillator (VCO), although that is not a requirement. Dividercontrol input may be provided by either the baseband circuitry 204 orthe applications processor 202 depending on the desired outputfrequency. In some embodiments, a divider control input (e.g., N) may bedetermined from a look-up table based on a channel indicated by theapplications processor 202.

Synthesizer circuitry 206 d of the RF circuitry 206 may include adivider, a delay-locked loop (DLL), a multiplexer and a phaseaccumulator. In some embodiments, the divider may be a dual modulusdivider (DMD) and the phase accumulator may be a digital phaseaccumulator (DPA). In some embodiments, the DMD may be configured todivide the input signal by either N or N+1 (e.g., based on a carry out)to provide a fractional division ratio. In some example embodiments, theDLL may include a set of cascaded, tunable, delay elements, a phasedetector, a charge pump and a D-type flip-flop. In these embodiments,the delay elements may be configured to break a VCO period up into Ndequal packets of phase, where Nd is the number of delay elements in thedelay line. In this way, the DLL provides negative feedback to helpensure that the total delay through the delay line is one VCO cycle.

In some embodiments, synthesizer circuitry 206 d may be configured togenerate a carrier frequency as the output frequency, while in otherembodiments, the output frequency may be a multiple of the carrierfrequency (e.g., twice the carrier frequency, four times the carrierfrequency) and used in conjunction with quadrature generator and dividercircuitry to generate multiple signals at the carrier frequency withmultiple different phases with respect to each other. In someembodiments, the output frequency may be a LO frequency (f_(LO)). Insome embodiments, the RF circuitry 206 may include an IQ/polarconverter.

FEM circuitry 208 may include a receive signal path which may includecircuitry configured to operate on RF signals received from one or moreantennas 210, amplify the received signals and provide the amplifiedversions of the received signals to the RF circuitry 206 for furtherprocessing. FEM circuitry 208 may also include a transmit signal pathwhich may include circuitry configured to amplify signals fortransmission provided by the RF circuitry 206 for transmission by one ormore of the one or more antennas 210.

In some embodiments, the FEM circuitry 208 may include a TX/RX switch toswitch between transmit mode and receive mode operation. The FEMcircuitry may include a receive signal path and a transmit signal path.The receive signal path of the FEM circuitry may include a low-noiseamplifier (LNA) to amplify received RF signals and provide the amplifiedreceived RF signals as an output (e.g., to the RF circuitry 206). Thetransmit signal path of the FEM circuitry 208 may include a poweramplifier (PA) to amplify input RF signals (e.g., provided by RFcircuitry 206), and one or more filters to generate RF signals forsubsequent transmission (e.g., by one or more of the one or moreantennas 210).

In some embodiments, the UE 200 may include additional elements such as,for example, memory/storage, display, camera, sensor, and/orinput/output (I/O) interface as described in more detail below. In someembodiments, the UE 200 described herein may be part of a portablewireless communication device, such as a personal digital assistant(PDA), a laptop or portable computer with wireless communicationcapability, a web tablet, a wireless telephone, a smartphone, a wirelessheadset, a pager, an instant messaging device, a digital camera, anaccess point, a television, a medical device (e.g., a heart ratemonitor, a blood pressure monitor, etc.), or other device that mayreceive and/or transmit information wirelessly. In some embodiments, theUE 200 may include one or more user interfaces designed to enable userinteraction with the system and/or peripheral component interfacesdesigned to enable peripheral component interaction with the system. Forexample, the UE 200 may include one or more of a keyboard, a keypad, atouchpad, a display, a sensor, a non-volatile memory port, a universalserial bus (USB) port, an audio jack, a power supply interface, one ormore antennas, a graphics processor, an application processor, aspeaker, a microphone, and other I/O components. The display may be anLCD or LED screen including a touch screen. The sensor may include agyro sensor, an accelerometer, a proximity sensor, an ambient lightsensor, and a positioning unit. The positioning unit may communicatewith components of a positioning network, e.g., a global positioningsystem (GPS) satellite.

The antennas 210 may comprise one or more directional or omnidirectionalantennas, including, for example, dipole antennas, monopole antennas,patch antennas, loop antennas, microstrip antennas or other types ofantennas suitable for transmission of RF signals. In some multiple-inputmultiple-output (MIMO) embodiments, the antennas 210 may be effectivelyseparated to take advantage of spatial diversity and the differentchannel characteristics that may result.

Although the UE 200 is illustrated as having several separate functionalelements, one or more of the functional elements may be combined and maybe implemented by combinations of software-configured elements, such asprocessing elements including digital signal processors (DSPs), and/orother hardware elements. For example, some elements may comprise one ormore microprocessors, DSPs, field-programmable gate arrays (FPGAs),application specific integrated circuits (ASICs), radio-frequencyintegrated circuits (RFICs) and combinations of various hardware andlogic circuitry for performing at least the functions described herein.In some embodiments, the functional elements may refer to one or moreprocesses operating on one or more processing elements.

Embodiments may be implemented in one or a combination of hardware,firmware and software. Embodiments may also be implemented asinstructions stored on a computer-readable storage device, which may beread and executed by at least one processor to perform the operationsdescribed herein. A computer-readable storage device may include anynon-transitory mechanism for storing information in a form readable by amachine (e.g., a computer). For example, a computer-readable storagedevice may include read-only memory (ROM), random-access memory (RAM),magnetic disk storage media, optical storage media, flash-memorydevices, and other storage devices and media. Some embodiments mayinclude one or more processors and may be configured with instructionsstored on a computer-readable storage device.

FIG. 3 is a block diagram of a communication device in accordance withsome embodiments. The device may be a UE or eNB, for example, such asthe UE 102 or eNB 104 shown in FIG. 1 that may be configured to trackthe UE as described herein. The physical layer circuitry 302 may performvarious encoding and decoding functions that may include formation ofbaseband signals for transmission and decoding of received signals. Thecommunication device 300 may also include medium access control layer(MAC) circuitry 304 for controlling access to the wireless medium. Thecommunication device 300 may also include processing circuitry 306, suchas one or more single-core or multi-core processors, and memory 308arranged to perform the operations described herein. The physical layercircuitry 302, MAC circuitry 304 and processing circuitry 306 may handlevarious radio control functions that enable communication with one ormore radio networks compatible with one or more radio technologies and,for example, may contain an LTE stack. The radio control functions mayinclude signal modulation, encoding, decoding, radio frequency shifting,etc. For example, similar to the device shown in FIG. 2, in someembodiments, communication may be enabled with one or more of a WMAN, aWLAN, and a WPAN. In some embodiments, the communication device 300 canbe configured to operate in accordance with 3GPP standards or otherprotocols or standards, including WiMax, WiFi, WiGig, GSM, EDGE, GERAN,UMTS, UTRAN, or other 3G, 3G, 4G, 5G, etc. technologies either alreadydeveloped or to be developed. The communication device 300 may includetransceiver circuitry 312 to enable communication with other externaldevices wirelessly and interfaces 314 to enable wired communication withother external devices. As another example, the transceiver circuitry312 may perform various transmission and reception functions such asconversion of signals between a baseband range and a Radio Frequency(RF) range.

The antennas 301 may comprise one or more directional or omnidirectionalantennas, including, for example, dipole antennas, monopole antennas,patch antennas, loop antennas, microstrip antennas or other types ofantennas suitable for transmission of RF signals. In some MIMOembodiments, the antennas 301 may be effectively separated to takeadvantage of spatial diversity and the different channel characteristicsthat may result.

Although the communication device 300 is illustrated as having severalseparate functional elements, one or more of the functional elements maybe combined and may be implemented by combinations ofsoftware-configured elements, such as processing elements includingDSPs, and/or other hardware elements. For example, some elements maycomprise one or more microprocessors, DSPs, FPGAs, ASICs, RFICs andcombinations of various hardware and logic circuitry for performing atleast the functions described herein. In some embodiments, thefunctional elements may refer to one or more processes operating on oneor more processing elements. Embodiments may be implemented in one or acombination of hardware, firmware and software. Embodiments may also beimplemented as instructions stored on a computer-readable storagedevice, which may be read and executed by at least one processor toperform the operations described herein.

FIG. 4 illustrates another block diagram of a communication device inaccordance with some embodiments. In alternative embodiments, thecommunication device 400 may operate as a standalone device or may beconnected (e.g., networked) to other communication devices. In anetworked deployment, the communication device 400 may operate in thecapacity of a server communication device, a client communicationdevice, or both in server-client network environments. In an example,the communication device 400 may act as a peer communication device inpeer-to-peer (P2P) (or other distributed) network environment. Thecommunication device 400 may be a UE, eNB, PC, a tablet PC, a STB, aPDA, a mobile telephone, a smart phone, a web appliance, a networkrouter, switch or bridge, or any communication device capable ofexecuting instructions (sequential or otherwise) that specify actions tobe taken by that communication device. Further, while only a singlecommunication device is illustrated, the term “communication device”shall also be taken to include any collection of communication devicesthat individually or jointly execute a set (or multiple sets) ofinstructions to perform any one or more of the methodologies discussedherein, such as cloud computing, software as a service (SaaS), othercomputer cluster configurations.

Examples, as described herein, may include, or may operate on, logic ora number of components, modules, or mechanisms. Modules are tangibleentities (e.g., hardware) capable of performing specified operations andmay be configured or arranged in a certain manner. In an example,circuits may be arranged (e.g., internally or with respect to externalentities such as other circuits) in a specified manner as a module. Inan example, the whole or part of one or more computer systems (e.g., astandalone, client or server computer system) or one or more hardwareprocessors may be configured by firmware or software (e.g.,instructions, an application portion, or an application) as a modulethat operates to perform specified operations. In an example, thesoftware may reside on a communication device readable medium. In anexample, the software, when executed by the underlying hardware of themodule, causes the hardware to perform the specified operations.

Accordingly, the term “module” is understood to encompass a tangibleentity, be that an entity that is physically constructed, specificallyconfigured (e.g., hardwired), or temporarily (e.g., transitorily)configured (e.g., programmed) to operate in a specified manner or toperform part or all of any operation described herein. Consideringexamples in which modules are temporarily configured, each of themodules need not be instantiated at any one moment in time. For example,where the modules comprise a general-purpose hardware processorconfigured using software, the general-purpose hardware processor may beconfigured as respective different modules at different times. Softwaremay accordingly configure a hardware processor, for example, toconstitute a particular module at one instance of time and to constitutea different module at a different instance of time.

Communication device (e.g., computer system) 400 may include a hardwareprocessor 402 (e.g., a central processing unit (CPU), a graphicsprocessing unit (GPU), a hardware processor core, or any combinationthereof), a main memory 404 and a static memory 406, some or all ofwhich may communicate with each other via an interlink (e.g., bus) 408.The communication device 400 may further include a display unit 410, analphanumeric input device 412 (e.g., a keyboard), and a user interface(UI) navigation device 414 (e.g., a mouse). In an example, the displayunit 410, input device 412 and UI navigation device 414 may be a touchscreen display. The communication device 400 may additionally include astorage device (e.g., drive unit) 416, a signal generation device 418(e.g., a speaker), a network interface device 420, and one or moresensors 421, such as a global positioning system (GPS) sensor, compass,accelerometer, or other sensor. The communication device 400 may includean output controller 428, such as a serial (e.g., universal serial bus(USB), parallel, or other wired or wireless (e.g., infrared (IR), nearfield communication (NFC), etc.) connection to communicate or controlone or more peripheral devices (e.g., a printer, card reader, etc.).

The storage device 416 may include a communication device readablemedium 422 on which is stored one or more sets of data structures orinstructions 424 (e.g., software) embodying or utilized by any one ormore of the techniques or functions described herein. The instructions424 may also reside, completely or at least partially, within the mainmemory 404, within static memory 406, or within the hardware processor402 during execution thereof by the communication device 400. In anexample, one or any combination of the hardware processor 402, the mainmemory 404, the static memory 406, or the storage device 416 mayconstitute communication device readable media.

While the communication device readable medium 422 is illustrated as asingle medium, the term “communication device readable medium” mayinclude a single medium or multiple media (e.g., a centralized ordistributed database, and/or associated caches and servers) configuredto store the one or more instructions 424.

The term “communication device readable medium” may include any mediumthat is capable of storing, encoding, or carrying instructions forexecution by the communication device 400 and that cause thecommunication device 400 to perform any one or more of the techniques ofthe present disclosure, or that is capable of storing, encoding orcarrying data structures used by or associated with such instructions.Non-limiting communication device readable medium examples may includesolid-state memories, and optical and magnetic media. Specific examplesof communication device readable media may include: non-volatile memory,such as semiconductor memory devices (e.g., Electrically ProgrammableRead-Only Memory (EPROM), Electrically Erasable Programmable Read-OnlyMemory (EEPROM)) and flash memory devices; magnetic disks, such asinternal hard disks and removable disks; magneto-optical disks; RandomAccess Memory (RAM); and CD-ROM and DVD-ROM disks. In some examples,communication device readable media may include non-transitorycommunication device readable media. In some examples, communicationdevice readable media may include communication device readable mediathat is not a transitory propagating signal.

The instructions 424 may further be transmitted or received over acommunications network 426 using a transmission medium via the networkinterface device 420 utilizing any one of a number of transfer protocols(e.g., frame relay, internet protocol (IP), transmission controlprotocol (TCP), user datagram protocol (UDP), hypertext transferprotocol (HTTP), etc.). Example communication networks may include alocal area network (LAN), a wide area network (WAN), a packet datanetwork (e.g., the Internet), mobile telephone networks (e.g., cellularnetworks), Plain Old Telephone (POTS) networks, and wireless datanetworks (e.g., Institute of Electrical and Electronics Engineers (IEEE)802.11 family of standards known as Wi-Fi®, IEEE 802.16 family ofstandards known as WiMax®), IEEE 802.15.4 family of standards, a LongTerm Evolution (LTE) family of standards, a Universal MobileTelecommunications System (UMTS) family of standards, peer-to-peer (P2P)networks, among others. In an example, the network interface device 420may include one or more physical jacks (e.g., Ethernet, coaxial, orphone jacks) or one or more antennas to connect to the communicationsnetwork 426. In an example, the network interface device 420 may includea plurality of antennas to wirelessly communicate using at least one ofsingle-input multiple-output (SIMO), MIMO, or multiple-inputsingle-output (MISO) techniques. In some examples, the network interfacedevice 420 may wirelessly communicate using Multiple User MIMOtechniques. The term “transmission medium” shall be taken to include anyintangible medium that is capable of storing, encoding or carryinginstructions for execution by the communication device 400, and includesdigital or analog communications signals or other intangible medium tofacilitate communication of such software.

As shown in FIGS. 1-4, various types of reference signals may betransmitted by an eNB for a UE to measure. The different referencesignals may include, for example, cell-specific reference signals (CRS)used for cell search and initial acquisition, demodulation and channelquality estimation and UE-specific reference signals (DMRS) for PDSCHdemodulation by the UE, as well as for handover. The number and type ofdownlink reference signals has increased with newer generations of LTEnetworks. This has led to issues regarding placement of the referencesignals as well as with balance of the reference signal load with datatransmission. Such issues have moreover become complicated with theadvent of MIMO systems, in which the same reference signals may betransmitted on different beams from the same eNB but using differentresource blocks. In particular, the introduction of massive MIMO systemshave only added to reference signal issues to an even greater extent dueto the increased number of antennas, antenna panels and antenna ports.Massive MIMO systems may contain at present multiple antenna panels,each of which may contain 64-128 antennas. As 5G and further systemsbecome more advanced. In various MIMO systems, the eNB and/or UE mayemploy beamforming to increase data throughput or quality. Differentreference signals may be transmitted by the eNB in each beam for powermeasurement by the UEs serviced by the eNB and beam selection. Thesereference signals (referred to as Beamformed Reference Signals (BRSs))may be located in different symbols within a subframe, with at leastsome of the remaining resource blocks in the subframe used fortransmitting data. Because of the disparity between the BRS allocationsin the different transmit beamformed signals, however, UEs that usereceive beamforming may be unable to simultaneously measure thebeamforming power and receive downlink data.

Specifically, it may be desirable for a UE to measure the power of abeamformed reference signal (BRS) (BRS received power or BRS-RP). InMIMO systems, the eNB may transmit different beamformed referencesignals in the PDSCH on the different antennas. In particular, thedifferent beamformed reference signal may use different sequences toenable the UE to distinguish between the various beamformed referencesignals. The sequences may be similar to those used for SecondarySynchronization Signal (SSS) sequences, which may be an interleavedconcatenation of two length-31 binary sequences scrambled with ascrambling sequence given by the Primary Synchronization Signal (PSS).In some embodiments, the BRS transmitted from each eNB antenna port maybe a cyclic shift of a base sequence. In some embodiments, the UE mayperform a scan to determine which BRS to measure the BRS-RP andsubsequently transmit BRS-RP information as well as identity informationof the beam and UE. This information, for example, may enable the eNB todetermine the best direction for transmitting data to the UE.

As above, in massive MIMO systems (either MU-MIMO or SU-MIMO systems) inaddition to each beam using a different BRS sequence, the eNB mayallocate different resource blocks in the PDSCH for transmission of thedifferent BRS. The eNB may thus transmit data and BRS in the PDSCH tothe same UE; the location of the BRS may, however, vary within thesubframe with the allocated resource block. This may cause an issue incircumstances in which the UE also has multiple antenna panels and usesreceiving beamforming, in which the UE receives multiple beams, as theUE may not be able to use the different beams to simultaneously measurethe BRS-RP and receive the data from the eNB.

To this end, the eNB may adjust transmission of the BRS within the beamsdependent on the recipient (UE) antenna capabilities, such as the numberof antenna panels of the recipient. However, to accomplish this, it maybe desirable for the eNB to obtain information regarding the UE antennacapabilities, and thus MIMO capabilities. In some embodiments, the UEmay provide the UE antenna information during initial attachment to theeNB, such as in an Attach Request, or during handover in a Tracking AreaUpdate message. Alternatively, once the UE is registered with the eNB,the eNB may transmit a dedicated message in the PDCCH or PDSCH to the UErequesting the UE antenna information. In some embodiments, the eNB mayobtain the UE antenna information from the MME or from the home networkof the UE (such as via a Home Subscriber Server (HSS)) or othernetwork-based server storing UE characteristics. For example, the eNBmay only request the antenna information after determining to but priorto providing MIMO signals to the UE.

The UE antenna information may include whether the UE has a singleantenna panel (i.e., only one antenna panel) or multiple antenna panelsfor serving eNB reception. The UE antenna information may specificallyinclude the number of antenna panels. The UE antenna information mayfurther include parameters for each antenna panel such as whether the UEantenna panel supports receiver beamforming, the number of digitalchains per antenna panel, and the number of receiver and transmitterantenna ports. Thus, in some embodiments, the number of antenna panelsand the number of digital streams each antenna panel is capable ofreceiving, as well as which of the UE antenna panels (if any) supportsreceiver beamforming, may be included in a UE capability enquiry messagecontaining the UE antenna information. A UE capability enquiry messagecontaining the UE antenna information may be transmitted by UEinitiation or in response to an external event, such as a request fromthe eNB or the UE being handed over from one eNB to another.

After the UE antenna information is received by the eNB, the eNB maycommunicate with the UE using MIMO FIG. 5 illustrates communicationsbetween an eNB and UE in accordance with some embodiments. In FIG. 5,the UE 504 may have a single antenna panel 504 a for reception ofcommunications from the eNB 502. In other embodiments, described below,the UE 504 may have a multiple antenna panels 504 a, 504 b. The eNB 502may transmit different BRS in different resource blocks in differentbeams. In this case, the UE 504 may be unable to determine the bestreceiver beam from the eNB 502. The UE 504 may be unable tosimultaneously measure and track the BRS and decode the EPDCCH/PDSCH,all of which are contained in one subframe. To circumvent this, ratherthan using each BRS opportunity, in some embodiments the eNB 502 maytransmit and/or the UE 504 may periodically perform BRS measurements. Asindicated below, the structure of either or both the BRS subframe (e.g.,what else is in the subframe) and structure of the beams (e.g., whichbeams carry information for the UE 504) may be dependent on antennainformation of the UE 504.

In some embodiments, the BRS measurement may be enabled for reception bythe UE 504 every K BRS subframes or frames, with a subframe or frameoffset K_(offset). The period K may be a non-zero integer value, such asan integer value that is greater than 1, with K_(offset) taking a valuefrom 0 to K−1. The period K and subframe offset K_(offset) may beconfigured by dedicated RRC signaling from the eNB 502 to the UE 504. Insome embodiments, in which multiple UEs 504 are served by the eNB 502,the period K and subframe offset K_(offset) may be configuredindividually for each UE 504 so that one or both the values may changefor each UE 504. In the example shown in FIG. 5, K=5 and K_(offset)=0,thus subframe 1 and subframe 6 contain the BRS (BRS subframes) and forwhich the UE is configured to measure the BRS-RP, with the remainingsubframes carrying a PDSCH for the UE. In some embodiments, the beam ofwhich the BRS is measured may change each time the UE measures the BRS.In some embodiments, the beam of which the BRS is measured by the UE maychange after multiple measurements of the BRS of the same beam. In someembodiments, the BRS may be allocated to the same resource blocks amongthe beams (and thus subframes); in other embodiments, the resourceblocks on which the BRS is located may vary with the beam or subframe.To perform a single beam searching (i.e., measure BRS of all of thebeams a single time) to select the optimal beam, may thus take M BRSsubframes, where M is K×the number of beams. The BRS-RP measurement maythen occur in the BRS subframes:0≤(n _(sf) mod T _(BRS))mod K−K _(offset) <M

where n_(sf) indicates the subframe number (SFN), T_(BRS) represents theBRS subframe period (e.g., T_(BRS)=25) and M may be configured by RRCsignaling. For a BRS subframe when the BRS measurement is not enabled,the UE 504 and the eNB 502 may consider the BRS subframe as a normaldownlink data subframe (i.e., without the BRS), also referred to as aPDSCH subframe. Unlike the BRS subframes, which the eNB 502 does notschedule (and thus do not contain) either an EPDDCH or PDSCH for the UE502, the PDSCH subframes may contain PDSCH for the UE 504. The PDSCHsubframes are denoted by the subframes 2-5 in FIG. 5. In otherembodiments, select the optimal beam multiple BRS-RP measurements of thesame beam may be taken, for example, consecutively or separated by M BRSsubframes.

After measurement and determination of the BRS-RP for each beam, theoptimal beam may be selected by the UE 504 for EPDCCH and PDSCHdecoding. For BRS subframes (as above, subframes 1 and 6 in FIG. 5), theeNB 502 may not schedule any uplink grant or downlink data for the UE504 and the UE 504 may use the different receive beams for BRS-RPmeasurement and beam tracking. In some embodiments, a default period Kmay be set to be one. Thus, the BRS subframe may be reserved exclusivelyfor transmit/receive beam acquisition and tracking.

In the above embodiment, the UE 504 may have a single antenna port aswell as a single antenna panel. In some embodiments, the UE 504 may havea single antenna panel but more than one receiver antenna port. In thiscase, the UE 504 may use one or more of the antenna ports for EPDCCH andPDSCH decoding and the remainder for BRS-RP measurement in the subframe.The UE 504 may report to the eNB 502 a BRS CSI measured from thereceiver antenna ports used for EPDCCH and PDSCH decoding in the BRSsubframe. The BRS CSI may be reported in a different CSI process (a BRSCSI process) than the normal CSI process that contains the CSI measuredfor the EPDCCH and PDSCH from all receiver antenna ports. The BRS CSIreport may include an indication that the CSI is a BRS CSI.

In other embodiments, rather than a single antenna panel, the UE 504 maycontain multiple antenna panels used to communicate with the eNB 502.The use of each antenna panel may be independent of any other antennapanel. In some embodiments, a particular antenna panel may be useddifferent purposes (e.g., BRS or EPDCCH/PDSCH reception) in eachsubframe or set of subframes. The UE 504 may, for example, reserve one(or more) antenna panel to receive the EPDCCH and PDSCH from the eNB 502while the remaining antenna panels may be used to track and refine beamsin the BRS subframe using the BRS. An antenna panel that receives theEPDCCH and PDSCH may be referred to as a reserved antenna panel, whilethe antenna panel used to track and refine beams using the BRS may bereferred to as an active antenna panel. In some embodiments, differentantenna panels of the UE 504 may be used to receive the EPDCCH and PDSCHin different subframes.

In some embodiments, a particular antenna panel of the multiple antennapanels of the UE 504 may receive the EPDCCH and PDSCH every n/msubframes, where n is the number of antenna panels and m is the numberof antenna panels in the set of antenna panels receiving the EPDCCH andPDSCH in that particular subframe, thereby rotating reception of theEPDCCH and PDSCH among the antenna panels equally. For example, if m=1,the eNB 502 may thus configure the UE 504 such that multiple antennapanels have the same BRS tracking period K (K=number of antenna panels)and each antenna panel has a different panel specific measurement shift(K_(offset)−0, 1, . . . , K−1).

In some embodiments, the particular antenna panel of the multipleantenna panels of the UE 504 may receive the EPDCCH and PDSCH for pconsecutive subframes. If a plurality of antenna panels receive theEPDCCH and PDSCH for p consecutive subframes, in some embodiments, theantenna panels may all receive the EPDCCH and PDSCH for the same pconsecutive subframes or, in other embodiments, the p consecutivesubframes may be staggered among the antenna panels such that at leastone of the antenna panels receiving the EPDCCH and PDSCH changes witheach subframe or set of subframes. The antenna panels that receive theEPDCCH and PDSCH in a particular subframe may be disposed in anylocation—e.g., adjacent to each other or separated by at least oneantenna panel in various embodiments. The specific antenna panelconfiguration, including values n, m, p, for the UE 504 to use in EPDCCHand PDSCH decoding and beam tracking and refinement in BRS subframes maybe provided from the eNB 502, for example, in dedicated RRC signaling.Thus, each antenna panel may have periodic opportunities to track andrefine transmitter and receiver beams.

The omni-directional BRS signals may be measured using the activeantenna panel and reported to the eNB 502 by the UE 504. In someembodiments, when the reserved antenna panel is a directional antennapanel, the simultaneous BRS-RP measurement for all antenna panels may beenabled periodically and the eNB 502 may not schedule an EPDCCH or PDSCHfor the UE 504. As above, the period and subframe offset may beconfigured by dedicated RRC signaling. In other embodiments, the BRS-RPmeasurement obtained using the reserved antenna panel may be enabledperiodically, and the active antenna panel may be used to decode EPDCCHand PDSCH in the BRS subframes when the reserved antenna panel is usedfor measurement.

As the EPDCCH and PDSCH may be decoded by different antenna panels withdifferent receive beams in the UE 504, the CSI measured from differentantenna panels may be reported by the UE 504. In some embodiments, theCSI measured from different antenna panels may be reported in differentCSI processes. In configuring the CSI, a bit may be added by the eNB 502in the RRC configuration to the UE 504 to indicate whether the CSI is tobe from a reserved antenna panel or from an active antenna panel. Forexample, the CSI bit may take value 0 to indicate the CSI is configuredfor active antenna panels and value 1 to indicate the reserved antennapanel CSI configuration. In some embodiments, the UE 504 may beinstructed to use one or more antenna panels for a CSI measurement ofthe BRS via Downlink Control Information (DCI). For example, value 0 mayindicate the CSI measured from active antenna panels should be reportedand value 1 may indicate the reserved antenna panel CSI should bereported by the UE 504.

FIG. 6 illustrates a method of BRS measurement in accordance with someembodiments. The method may be carried out by the UEs in any of FIGS.1-5. At operation 602, the UE may provide the eNB with antennainformation. The antenna information may be provided at admissioncontrol, when the UE initially attaches to the eNB, or later.Transmission of the antenna information may be initiated by the UE ormay be requested by the eNB. The antenna information may include thenumber of antenna panels of the UE, as well as parameters for eachantenna panel such as whether the UE antenna panel supports receiverbeamforming, the number of digital chains per antenna panel, and thenumber of receiver and transmitter antenna ports.

The antenna information may also include whether the UE uses MIMOreception. This information may be used by the eNB to determine themanner to trigger reception of the BRS subframes by the UE. The UE mayreceive at operation 604 the BRS subframe configuration information inan RRC message from the eNB or in a system information broadcast, forexample. This may include the periodicity and offset for the BRSsubframes for each antenna panel.

After having transmitted the antenna information to the eNB and receivedthe BRS configuration information, the UE may at operation 606 receiveBRS subframes from the eNB. The BRS subframes may, if the UE is capableof MIMO reception, be received in predetermined sets of downlinksubframes such as in every downlink subframe. The BRS in different beamsand/or subframes may be in different resource blocks. Alternatively, theUE may receive or perform BRS subframes only periodically. The BRSsubframes may be received every K subframes or frames, with a subframeoffset K_(offset). The period K and subframe offset K_(offset) may beconfigured by dedicated RRC signaling from the eNB to the UE. In variousembodiments, the beam that carries the BRS sequence may change each timethe UE measures the BRS and may be allocated to the same resource blocksamong the beams or may vary with the beam or subframe. The UE mayreceive PDSCH subframes, which may or may not contain data for the UE,between the BRS subframes.

Regardless of the manner in which the UE receives the BRS in one of theBRS subframes, at operation 608, the UE may measure the BRS-RP of theBRS. After measuring the BRS-RP of each beam at least once, an optimalreceiver beam (with the highest BRS-RP) may be selected by the UE forEPDCCH and PDSCH decoding. The BRS subframe may be reserved by the UEexclusively for transmit/receive beam acquisition and tracking. The UEmay perform fine beam tracking using the BRS-RP. If the UE has multipleantenna ports or panels, the UE may use one or more of the antenna portsor panels for EPDCCH and PDSCH decoding and the remainder for BRS-RPmeasurement in a subframe.

At operation 610, the UE may transmit BRS information to the eNB. Thisinformation may include either or both the BRS-RP measurements and theoptimal receiver beam. The UE may report the BRS CSI measured from thereceiver antenna ports used for EPDCCH and PDSCH decoding in the BRSsubframe. The BRS CSI may be reported in a different CSI process (BRSCSI process) than the normal CSI processing. If the CSI is measured fromdifferent antenna panels by the UE, the different CSIs may be indicatedusing unique indicators to indicate whether the CSI is from a reservedantenna panel or from an active antenna panel.

Example 1 is an apparatus of user equipment (UE) comprising processingcircuitry arranged to: decode a MIMO beamformed Reference Signal (BRS)subframe in one of a plurality of simultaneous Multiple Input MultipleOutput (MIMO) beams from an evolved Node-B (eNB), the BRS subframecomprising a BRS, wherein a structure of the BRS subframe and astructure of a BRS subframe of at least another of the simultaneous MIMObeams is dependent on antenna information of the UE; and measure BRSReceived Power (BRS-RP) of the BRS; generate a BRS report based on theBRS-RP.

In Example 2, the subject matter of Example 1 optionally includes thatthe structure of the BRS subframe comprises inclusion of at least one ofdata and control signals for the UE.

In Example 3, the subject matter of any one or more of Examples 1-2optionally include that the BRS in each simultaneous MIMO beam comprisesa different BRS sequence that uniquely identifies an associated one ofthe simultaneous MIMO beams.

In Example 4, the subject matter of any one or more of Examples 1-3optionally include that the BRS in at least one of the simultaneous MIMObeams is allocated to a different resource block from the BRS in atleast one other of the simultaneous MIMO beams.

In Example 5, the subject matter of any one or more of Examples 1-4optionally include that the BRS in different BRS subframes of one of thesimultaneous MIMO beams are allocated to different resource blocks.

In Example 6, the subject matter of any one or more of Examples 1-5optionally include a transceiver arranged to communicate with the eNB,the transceiver arranged to transmit, to the eNB prior to reception ofthe BRS subframe, the antenna information, the antenna informationcomprising at least one of a number of antenna panels of the UE, whethereach UE antenna panel supports receiver beamforming, a number of digitalchains per antenna panel, and a number of receiver and transmitterantenna ports for each antenna panel.

In Example 7, the subject matter of any one or more of Examples 1-6optionally include a single antenna panel, wherein the BRS subframe isfree from at least one of an enhanced physical downlink control channel(EPDCCH) and physical downlink shared channel (PDSCH) for the UE.

In Example 8, the subject matter of any one or more of Examples 1-7optionally include a single antenna panel, wherein the processingcircuitry is further arranged to: periodically measure the BRS-RP everyK subframes with a subframe offset Koffset, where K is a non-zerointeger value and Koffset has a value from 0 to K−1, and decode at leastone of an enhanced physical downlink control channel (EPDCCH) andphysical downlink shared channel (PDSCH) for subframes other than BRSsubframes.

In Example 9, the subject matter of Example 8 optionally includes atransceiver arranged to communicate with the eNB, the transceiverarranged to receive K and Koffset in a Radio Resource Control (RRC)signal prior to reception of the BRS subframe.

In Example 10, the subject matter of any one or more of Examples 8-9optionally include that the processing circuitry is further arranged to:measure the BRS-RP of a different simultaneous MIMO beam every Ksubframes.

In Example 11, the subject matter of any one or more of Examples 1-10optionally include a single antenna panel comprising a plurality ofantenna ports comprising a first set of the antenna ports configured toreceive the BRS in the BRS subframe and a second set of the antennaports configured to receive an enhanced physical downlink controlchannel (EPDCCH) and a physical downlink shared channel (PDSCH) in theBRS subframe.

In Example 12, the subject matter of any one or more of Examples 1-11optionally include a plurality of antenna panels comprising at least oneactive antenna panel each configured to receive a BRS in a BRS subframeof a different simultaneous MIMO beam and at least one reserved antennapanel each configured to receive at least one of an enhanced physicaldownlink control channel (EPDCCH) and physical downlink shared channel(PDSCH) in each of the BRS subframes of the different simultaneous MIMObeams.

In Example 13, the subject matter of Example 12 optionally includes,wherein the processing circuitry is further arranged to: determine aChannel State Information (CSI) configuration for each of the at leastone active antenna panel and the at least one reserved antenna panelfrom a Radio Resource Control (RRC) signal, the CSI configurationcomprising an indication for which of the at least one active antennapanel and the at least one reserved antenna panel the CSI configurationis intended.

In Example 14, the subject matter of any one or more of Examples 12-13optionally include that the processing circuitry is further arranged to:determine a Channel State Information (CSI) trigger for each of the atleast one active antenna panel and the at least one reserved antennapanel from Downlink Control Information (DCI), the CSI triggercomprising an indication which of the at least one active antenna paneland the at least one reserved antenna panel the CSI trigger is to reporta CSI measurement.

In Example 15, the subject matter of any one or more of Examples 12-14optionally include that the processing circuitry is further arranged to:periodically measure, for each antenna panel, the BRS-RP every Ksubframes with a subframe offset Koffset, where K is a non-zero integervalue and Koffset has a value from 0 to K−1, and each antenna panel hasthe same K and different Koffset.

Example 16 is an apparatus of an evolved NodeB (eNB) comprisingprocessing circuitry arranged to: determine a MIMO beamformed ReferenceSignal (BRS) configuration based on antenna capacity of a user equipment(UE); generate a plurality of simultaneous Multiple Input MultipleOutput (MIMO) beams, at least one of the simultaneous MIMO beamscomprising a BRS subframe, the BRS subframe comprising a structuredependent on the UE antenna capacity; and process a report comprisingBRS Received Power (BRS-RP) of the BRS based on the BRS configuration.

In Example 17, the subject matter of Example 16 optionally includes thatthe structure of the BRS subframe comprises whether at least one of anenhanced physical downlink control channel (EPDCCH) and physicaldownlink shared channel (PDSCH) for the UE is in the BRS subframe.

In Example 18, the subject matter of Example 17 optionally includes thata structure of a BRS subframe of at least another the simultaneous MIMObeams is dependent on the antenna capacity.

In Example 19, the subject matter of any one or more of Examples 17-18optionally include at least one of: the BRS in each simultaneous MIMObeam comprises a different BRS sequence that uniquely identifies theMIMO beam, the BRS in at least one of the simultaneous MIMO beams isallocated to a different resource block from the BRS in at least oneother of the simultaneous MIMO beams, and the BRS in different BRSsubframes of one of the simultaneous MIMO beams are allocated todifferent resource blocks.

In Example 20, the subject matter of any one or more of Examples 17-19optionally include that the processing circuitry is further arranged to:in response to the antenna capacity indicating that the UE comprises asingle antenna panel, generate a BRS subframe on the at least one of thesimultaneous MIMO beams every K subframes with a subframe offsetKoffset, in which each BRS subframe is free from at least one of anenhanced physical downlink control channel (EPDCCH) and physicaldownlink shared channel (PDSCH) for the UE.

In Example 21, the subject matter of any one or more of Examples 17-20optionally include that the processing circuitry is further arranged to:in response to the antenna capacity indicating that the UE comprises asingle antenna panel and a plurality of antenna ports, generate indifferent simultaneous MIMO beams a BRS subframe free from at least oneof an enhanced physical downlink control channel (EPDCCH) and physicaldownlink shared channel (PDSCH) for the UE to a first set of the antennaports configured to receive the BRS subframe and at least one of anEPDCCH and PDSCH for the UE to a second set of the antenna portsconfigured to receive the at least one of the EPDCCH and PDSCH in theBRS subframe.

In Example 22, the subject matter of any one or more of Examples 17-21optionally include that the processing circuitry is further arranged to:in response to the antenna capacity indicating that the UE comprises aplurality of antenna panels, generate in different simultaneous MIMObeams a BRS subframe comprising the BRS and an enhanced physicaldownlink control channel (EPDCCH) and physical downlink shared channel(PDSCH) for the UE.

Example 23 is a computer-readable storage medium that storesinstructions for execution by one or more processors of a user equipment(UE) to communicate with an evolved NodeB (eNB), the one or moreprocessors to configure the UE to: transmit to the eNB antenna capacityof the UE; receive from the eNB a beamformed Reference Signal (BRS)configuration based on the antenna capacity; receive a BRS subframecomprising a BRS in one of a plurality of simultaneous Multiple InputMultiple Output (MIMO) beams from the eNB, a structure of the BRSsubframe dependent on the antenna capacity, measure BRS Received Power(BRS-RP) of the BRS; transmit to the eNB a BRS report based on theBRS-RP; and select an optimal MIMO beam based on BRS-RPs from BRSs ofthe simultaneous MIMO beams.

In Example 24, the subject matter of Example 23 optionally includes,wherein: the structure of the BRS subframe comprises whether at leastone of an enhanced physical downlink control channel (EPDCCH) andphysical downlink shared channel (PDSCH) for the UE is in the BRSsubframe.

In Example 25, the subject matter of any one or more of Examples 23-24optionally include or 24, wherein the one or more processors furtherconfigure the UE to at least one of: receive a BRS subframe that is freefrom at least one of an enhanced physical downlink control channel(EPDCCH) and physical downlink shared channel (PDSCH) for the UE inresponse to the antenna information indicating that the UE comprises asingle antenna, receive at a first set of antenna ports the BRS in theBRS subframe and an EPDCCH and a PDSCH in the BRS subframe at a secondset of the antenna ports, in response to the antenna informationindicating that the UE comprises a single antenna comprising a pluralityof antenna ports, and receive, at each of at least one active antennapanel, a BRS in a BRS subframe of a different MIMO beam and, at each ofat least one reserved antenna panel, at least one of an EPDCCH and aPDSCH in each of the BRS subframes of the different simultaneous MIMObeams, in response to the antenna information indicating that the UEcomprises a plurality of antenna panels.

In Example 26, the subject matter of any one or more of Examples 23-25optionally include that the one or more processors further configure theUE to: perform a single beam searching to measure the BRS of all of thesimultaneous MIMO beams a single time to select the optimal simultaneousMIMO beam taking M BRS subframes, where M is K×a number of simultaneousMIMO beams, and measure the BRS-RP in BRS subframes defined by:0≤(n _(sf) mod T _(BRS))mod K−K _(offset) <Mwhere K as a non-zero integer value, subframe offset K_(offset) is avalue from 0 to K−1, n_(sf) is a subframe number (SFN), T_(BRS) is a BRSsubframe period and M, K and K_(offset) are configured by Radio ResourceControl (RRC) signaling.

Example 27 is a user equipment (UE) comprising: means for transmittingto the eNB antenna capacity of the UE; means for receiving from the eNBa beamformed Reference Signal (BRS) configuration based on the antennacapacity; means for receiving a BRS subframe comprising a BRS in one ofa plurality of simultaneous Multiple Input Multiple Output (MIMO) beamsfrom the eNB, a structure of the BRS subframe dependent on the antennacapacity; means for measuring BRS Received Power (BRS-RP) of the BRS;means for transmitting to an evolved NodeB (eNB) a BRS report based onthe BRS-RP; and means for selecting an optimal MIMO beam based onBRS-RPs from BRSs of the simultaneous MIMO beams.

In Example 28, the subject matter of Example 27 optionally includes thatthe structure of the BRS subframe comprises whether at least one of anenhanced physical downlink control channel (EPDCCH) and physicaldownlink shared channel (PDSCH) for the UE is in the BRS subframe.

In Example 29, the subject matter of Example 27 or 28 optionallyincludes that the UE further comprises: means for receiving a BRSsubframe that is free from at least one of an enhanced physical downlinkcontrol channel (EPDCCH) and physical downlink shared channel (PDSCH)for the UE in response to the antenna information indicating that the UEcomprises a single antenna, means for receiving at a first set ofantenna ports the BRS in the BRS subframe and an EPDCCH and a PDSCH inthe BRS subframe at a second set of the antenna ports, in response tothe antenna information indicating that the UE comprises a singleantenna comprising a plurality of antenna ports, and means forreceiving, at each of at least one active antenna panel, a BRS in a BRSsubframe of a different MIMO beam and, at each of at least one reservedantenna panel, at least one of an EPDCCH and a PDSCH in each of the BRSsubframes of the different simultaneous MIMO beams, in response to theantenna information indicating that the UE comprises a plurality ofantenna panels.

In Example 30, the subject matter of any one or more of Examples 27-29optionally include that the UE further comprises: means for performing asingle beam searching to measure the BRS of all of the simultaneous MIMObeams a single time to select the optimal simultaneous MIMO beam takingM BRS subframes, where M is K×a number of simultaneous MIMO beams, andmeans for measuring the BRS-RP in BRS subframes defined by:0≤(n _(sf) mod T _(BRS))mod K−K _(offset) <Mwhere K is a non-zero integer value, subframe offset K_(offset) is avalue from 0 to K−1, n_(sf) is a subframe number (SFN), T_(BRS) is a BRSsubframe period and M, K and K_(offset) are configured by Radio ResourceControl (RRC) signaling.

Although an embodiment has been described with reference to specificexample embodiments, it will be evident that various modifications andchanges may be made to these embodiments without departing from thebroader spirit and scope of the present disclosure. Accordingly, thespecification and drawings are to be regarded in an illustrative ratherthan a restrictive sense. The accompanying drawings that form a parthereof show, by way of illustration, and not of limitation, specificembodiments in which the subject matter may be practiced. Theembodiments illustrated are described in sufficient detail to enablethose skilled in the art to practice the teachings disclosed herein.Other embodiments may be utilized and derived therefrom, such thatstructural and logical substitutions and changes may be made withoutdeparting from the scope of this disclosure. This Detailed Description,therefore, is not to be taken in a limiting sense, and the scope ofvarious embodiments is defined only by the appended claims, along withthe full range of equivalents to which such claims are entitled.

Such embodiments of the inventive subject matter may be referred toherein, individually and/or collectively, by the term “embodiment”merely for convenience and without intending to voluntarily limit thescope of this application to any single embodiment or inventive conceptif more than one is in fact disclosed. Thus, although specificembodiments have been illustrated and described herein, it should beappreciated that any arrangement calculated to achieve the same purposemay be substituted for the specific embodiments shown. This disclosureis intended to cover any and all adaptations or variations of variousembodiments. Combinations of the above embodiments, and otherembodiments not specifically described herein, will be apparent to thoseof skill in the art upon reviewing the above description.

In this document, the terms “a” or “an” are used, as is common in patentdocuments, to include one or more than one, independent of any otherinstances or usages of“at least one” or “one or more.” In this document,the term “or” is used to refer to a nonexclusive or, such that “A or B”includes “A but not B,” “B but not A,” and “A and B,” unless otherwiseindicated. In this document, the terms “including” and “in which” areused as the plain-English equivalents of the respective terms“comprising” and “wherein.” Also, in the following claims, the terms“including” and “comprising” are open-ended, that is, a system, UE,article, composition, formulation, or process that includes elements inaddition to those listed after such a term in a claim are still deemedto fall within the scope of that claim. Moreover, in the followingclaims, the terms “first,” “second,” and “third,” etc. are used merelyas labels, and are not intended to impose numerical requirements ontheir objects.

The Abstract of the Disclosure is provided to comply with 37 C.F.R. §1.72(b), requiring an abstract that will allow the reader to quicklyascertain the nature of the technical disclosure. It is submitted withthe understanding that it will not be used to interpret or limit thescope or meaning of the claims. In addition, in the foregoing DetailedDescription, it can be seen that various features are grouped togetherin a single embodiment for the purpose of streamlining the disclosure.This method of disclosure is not to be interpreted as reflecting anintention that the claimed embodiments require more features than areexpressly recited in each claim. Rather, as the following claimsreflect, inventive subject matter lies in less than all features of asingle disclosed embodiment. Thus the following claims are herebyincorporated into the Detailed Description, with each claim standing onits own as a separate embodiment.

What is claimed is:
 1. An apparatus, comprising: processing circuitryarranged to cause a user equipment device (UE) to: receive, from a basestation, radio resource control (RRC) configuration information for abeamformed Reference Signal (BRS) including parameters indicative ofperiodicity and time offset for the BRS; receive, from the base station,the BRS during first time intervals, wherein the first time intervalsare determined from the RRC configuration information; refine a receivebeam associated with the BRS during the first time intervals, whereinthe UE does not receive enhanced physical downlink control channel(PDCCH) transmission during the first time intervals and when anenhanced PDCCH transmission is received, it is received during a secondtime interval different from the first time intervals; measure BRSReceived Power (BRS-RP) of the BRS; and generate a BRS report based onthe BRS-RP.
 2. The apparatus of claim 1, wherein the BRS comprises achannel state information (CSI) reference signal.
 3. The apparatus ofclaim 1, wherein the processing circuitry is further arranged to causethe UE to receive the BRS within third time intervals determined fromthe RRC configuration information.
 4. The apparatus of claim 1, whereinthe BRS in a plurality of additional subframes is associated with afirst transmit beam of the base station.
 5. The apparatus of claim 1,wherein the processing circuitry is further arranged to cause the UE to:provide antenna information to the base station, wherein the antennainformation includes a number of antenna panels of the UE.
 6. Theapparatus of claim 5, wherein the RRC configuration is based on theantenna information.
 7. The apparatus of claim 5, wherein to measure theBRS-RP of the BRS includes measuring BRS-RP using different antennapanels at different times.
 8. A user equipment (UE) comprising: a radio;and processing circuitry operably connected to the radio and arranged tocause the UE to: receive, from a base station, radio resource control(RRC) configuration information for a beamformed Reference Signal (BRS)including parameters indicative of periodicity and time offset for theBRS; receive the BRS during first time intervals, wherein the first timeintervals are determined from the RRC configuration information; refinea receive beam associated with the BRS during the first time intervals,wherein the UE does not receive enhanced physical downlink controlchannel (PDCCH) transmission during the first time intervals and when anenhanced PDCCH transmission is received, it is received during a secondtime interval different from the first time intervals; measure BRSReceived Power (BRS-RP) of the BRS; and generate a BRS report based onthe BRS-RP.
 9. The UE of claim 8, wherein the BRS comprises a channelstate information (CSI) reference signal.
 10. The UE of claim 8, whereinthe processing circuitry is further arranged to cause the UE to receivethe BRS within third time intervals determined from the RRCconfiguration information.
 11. The UE of claim 8, wherein the BRS in aplurality of additional subframes is associated with a first transmitbeam of the base station.
 12. The UE of claim 8, wherein the processingcircuitry is further arranged to cause the UE to: provide antennainformation to the base station, wherein the antenna informationincludes a number of antenna panels of the UE.
 13. The UE of claim 12,wherein the RRC configuration is based on the antenna information. 14.The UE of claim 12, wherein to measure the BRS-RP of the BRS includesmeasuring BRS-RP using different antenna panels at different times. 15.An apparatus, comprising: processing circuitry arranged to cause a basestation to: transmit, to user equipment device (UE), radio resourcecontrol (RRC) configuration information for a beamformed ReferenceSignal (BRS) including parameters indicative of periodicity and timeoffset for the BRS; transmit, to the UE, the BRS during first timeintervals, wherein the first time intervals are determined from the RRCconfiguration information, wherein the BRS is useable for the UE torefine a receive beam during the first time intervals, wherein the basestation does not transmit enhanced physical downlink control channel(PDCCH) transmission during the first time intervals; and receive, fromthe UE, a BRS report based on measured BRS Received Power (BRS-RP) ofthe BRS.
 16. The apparatus of claim 15, wherein the BRS comprises achannel state information (CSI) reference signal.
 17. The apparatus ofclaim 15, wherein the processing circuitry is further arranged to causethe base station to transmit the BRS within third time intervalsdetermined from the RRC configuration information.
 18. The apparatus ofclaim 15, wherein the BRS in a plurality of additional subframes isassociated with a first transmit beam of the base station.
 19. Theapparatus of claim 15, wherein the processing circuitry is furtherarranged to cause the base station to: receive, from the UE, antennainformation, wherein the antenna information includes a number ofantenna panels of the UE.
 20. The apparatus of claim 19, wherein the RRCconfiguration is based on the antenna information.